Dielectric performances of SF/sub 6/ impregnated polypropylene film capacitor

Capacitors with SF/sub 6/ impregnated polypropylene film insulation and edge-folded Al-foil design showed excellent dielectric performance. Al-foil edge folding can increase partial discharge inception and extinction stress in the gas adjacent to the electrode edges, and decrease dielectric losses. The cause of the dielectric loss increase of nonfolded samples at lower pressure is the occurrence of partial discharge in the gas adjacent to the electrode edges. The lightning impulse test affects dielectric losses, but no further changes of the dielectric loss are observed after nine impulses. Excellent overvoltage withstanding performance is shown, indicating that a capacitor with this insulation will be safe and reliable. >